For a cutting work of metal, a tool holder having a cutter blade affixed to its leading end is attached to a machine tool in a cantilevered manner. Hence, the problem of deterioration in the working accuracy may occur if there occurs a so-called “chattering vibration” in the tool holder in the course of a cutting work for cutting metal which is effected by driven revolution of the tool holder.
The above-described vibration damping mechanism is configured to cause the vibration damping weight accommodated in the hollow portion to be vibrated in such a manner to offset chattering vibration and also to absorb the energy of the chattering vibration if or when such chattering vibration occurs in the course of a cutting work, thereby to restrict this chattering vibration for achieving improvement in the working accuracy.
The conventional vibration damping mechanism is configured to be capable of absorbing chattering vibration energy through friction or impact between a single vibration damping weight accommodated within the hollow portion and the inner face of this hollow portion (see e.g. PTL 1).